Thin film transistor liquid crystal display and method for manufacturing the same

ABSTRACT

A thin film transistor liquid crystal display and method for manufacturing the same. The liquid crystal display comprises a TOC substrate, wherein a TFT is disposed on a color filter. A data line is disposed between the color filter and a lower substrate, also functioning as a black matrix. The TFT is coupled between the data line and a pixel electrode.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a color liquid-crystal display (LCD)panel and a manufacturing process thereof. In particular, it relates toa color liquid-crystal display panel comprising a switching element suchas a thin-film transistor (TFT), a color filter, and a black matrix on asingle substrate.

[0003] 2. Description of the Related Art

[0004] In general, a thin film transistor liquid crystal displayincludes a lower substrate, a thin film transistor, as a switchingdevice, formed on the lower substrate, an upper substrate opposite thelower substrate, a color filter of red, green and blue formed on theupper substrate and a liquid crystal sealed within a cavity defined byboth substrates.

[0005]FIG. 1 is a cross section showing a conventional thin filmtransistor liquid crystal display (TFT LCD).

[0006] An etch stopper inverse staggered type (7-mask process) thin filmtransistor 15 is disposed on a portion of a lower substrate 1 and apixel electrode 8 is disposed on the other portion of the lowersubstrate 1. The pixel electrode is of ITO. A passivation layer 9 forprotecting the TFT 15 is arranged on the TFT 15. The TFT 15 has a gate 2a, a source 7 a and a drain 7 b. A storage electrode 2 b on the sameplane as the gate 2 a, the pixel electrode 8 and an insulating layer 3interposed between the storage electrode 2 b and the pixel electrode 8,form a capacitor 17. A black matrix 12 is disposed on a portion of theupper substrate 11 for preventing crosstalk in the liquid crystaldisplay. The black matrix 12 is formed on a portion of the uppersubstrate corresponding to the TFT 15 and the capacitor 17. The colorfilter layer 13 of red, green and blue is disposed on another portion ofthe upper substrate which corresponds to the pixel electrode. A commonelectrode 14 is arranged on the black matrix 12 and the color filter 13.The common electrode 14 is of ITO. A numeral 4 indicates an activeregion, a numeral 5 indicates an etch stopper and a numeral 6 indicatesan ohmic resistance contact layer.

[0007] In order to manufacture such TFT LCD in one production line, theTFT 15 is formed on the portion of the lower substrate 1. During theformation of the TFT 15 before forming the source 7 a and the drain 7 b,the pixel electrode 8 is formed on the other portion of the lowersubstrate 1. Thereafter, the passivation layer 9, for protecting the TFT15 is formed thereon. In another production line, the black matrix 12 isformed on a portion of the upper substrate 11 corresponding to the TFT15 and the capacitor 17. The color filter layer 13 is formed on anotherportion of the upper substrate 11 corresponding to the pixel electrode8. Then the common electrode 14 is formed over the resultant portion inwhich the black matrix 12 and the color filter 13 are provided.

[0008] According to the above described manufacturing method, twoproduction lies are required to fabricate the TFT LCD, one for formationof the TFT 15 on the lower substrate 1 and the other for formation ofthe color filter layer 13 and the black matrix 12 on the upper substrate11. Investment and production costs are thus excessive.

[0009] In addition, the conventional liquid-crystal panel where thecolor filter 13 and the black matrix 12 are disposed on the uppersubstrate 11 facing an active-matrix substrate 1 must be manufacturedwith a given margin for alignment error which may occur during assembly.It has been, therefore, difficult to ensure the maximum area of thepixel opening (opening ratio).

SUMMARY OF THE INVENTION

[0010] Accordingly, an object of the present invention is to provide aspecific structure of an active matrix substrate with a color filter anda black matrix thereon.

[0011] The present invention provides a liquid crystal displaycomprising a first substrate, a second substrate having a commonelectrode opposite the first substrate, a switching device disposed on aportion of the first substrate, and the switching device coupled betweena data line and a pixel electrode, a color filter layer disposed betweenthe switching device and the first substrate, and the data line disposedbetween the color filter and the first substrate.

[0012] In a specific case, the data line also functions as a blackmatrix. An active matrix substrate with the color filter and the blackmatrix between the switching element such as a TFT and a glass substrateis referred to as TFT-on-CF substrate.

[0013] A source electrode of the switching element disposed on the colorfilter and the data line from M1, also functioning as black matrix isconnected to the local line. The local line can be an independentconducting line disposed over the passivation layer and connecting thesource electrode and the data line through two openings. Alternatively,the local line can be extending from the source electrode.

[0014] If the local line is the above-mentioned independent conductingline, the local line and the pixel electrode are the same transparentconducting material. The gate insulating layer can be disposed betweenthe passivation layer and the overcoat.

[0015] As for the local line extending from the source electrode, thesource electrode can be a metal material or transparent conductingmaterial.

[0016] If the source electrode is a metal material, that is, M3, thedrain electrode can be disposed over or under the pixel electrode. Insuch situations, the gate insulating layer should be disposedsubstantially over the entire lower substrate.

[0017] If the source electrode is a transparent conducting material, thedrain electrode extends to act as the pixel electrode. In suchsituations, the gate insulating layer should be disposed substantiallyover the entire lower substrate.

[0018] The present invention also provides a method for manufacturing aliquid crystal display comprising providing a substrate, forming a dataline thereon, forming a color filter on the data line and the substrate,forming an overcoat on the color filter, forming a switching device onthe overcoat, the switching device coupled between a data line and apixel electrode.

[0019] A source electrode of the switching element disposed on the colorfilter and the data line patterned from M1 also functioning as blackmatrix is connected to a local line. The local line can be formed by M3process with one opening, or pixel electrode process with one or twoopenings.

[0020] If the local line is patterned from M3, the local line is thesource electrode extends to contact the data line/black matrix. Theopening exposing the surface of the data line/black matrix is formed inthe overcoat and the gate dielectric layer and the gate dielectric layeris not patterned in the active region patterning process. Moreover, thepixel electrode can be formed before or after the M3 process.

[0021] If the local line is patterned from transparent conducting layerin the pixel electrode process and one opening for the local line isneeded, the local line and the pixel electrode are patterned at the sametime. The local line is the source electrode extends to contact the dataline/black matrix, and the pixel electrode extends to act as the drainelectrode. Therefore, M3 process is saved. Moreover, the openingexposing the surface of the data line/black matrix is formed in theovercoat and the gate dielectric layer, and the gate dielectric layer isnot patterned in the active region patterning process.

[0022] If the local line is patterned from transparent conducting layerin the pixel electrode process and two openings for the local line areneeded, the local line and the pixel electrode are patterned at the sametime and the two openings are formed to expose the surface of the sourceelectrode and the data line/black matrix respectively. The two openingscan be formed by one or two opening processes. For the former, theopening process is performed after forming the passivation layer, andthe opening is formed in the passivation layer and the overcoat or inthe passivation layer, the gate insulating layer and the overcoat, whichdepends on that if the gate dielectric layer is patterned in the activeregion patterning process or not patterned. For the latter, the firstopening process is performed after forming the overcoat and beforeforming the gate lines, and is formed in the overcoat, and the secondopening process is performed after forming the passivation layer and isformed in the passivation layer or in the passivation layer and the gatedielectric layer, which depends on whether the gate dielectric layer ispatterned in the active region patterning process.

[0023] By forming a color filter and a black matrix on an active matrixsubstrate, it is not necessary to consider an assembly margin, leadingto a more simplified manufacturing process and increase in pixel openingratio.

[0024] A detailed description is given in the following embodiments withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention can be more fully understood by reading thesubsequent detailed description and examples with references made to theaccompanying drawings, wherein:

[0026]FIG. 1 is a cross section of a liquid crystal display produced inaccordance with a conventional technique;

[0027]FIG. 2A-2G are cross sections showing a method for forming a TOCsubstrate of a liquid-crystal panel according to a first embodiment ofthis invention;

[0028]FIG. 3A-3G are cross sections showing a method for forming a TOCsubstrate of a liquid-crystal panel according to a second embodiment ofthis invention;

[0029]FIG. 4A-4G are cross sections showing a method for forming a TOCsubstrate of a liquid-crystal panel according to a third embodiment ofthis invention;

[0030]FIG. 5A-5E are cross sections showing a method for forming a TOCsubstrate of a liquid-crystal panel according to a fourth embodiment ofthis invention;

[0031]FIG. 6A-6H are cross sections showing a method for forming a TOCsubstrate of a liquid-crystal panel according to a fifth embodiment ofthis invention;

[0032]FIG. 7A-7H are cross sections showing a method for forming a TOCsubstrate of a liquid-crystal panel with a thicker passivation layeraccording to a sixth embodiment of this invention;

[0033]FIG. 8 is a cross section showing a method for forming a TOCsubstrate of a liquid-crystal panel with a conformal passivation layeraccording to a sixth embodiment of this invention;

[0034]FIG. 9A is a top view of a LCD with a TOC substrate according to aseventh embodiment of this invention;

[0035]FIG. 9B is a cross section taken along cut line B-B of FIG. 9A;

[0036]FIG. 9C is a cross section taken along cut line C-C of FIG. 9A;

[0037]FIG. 10A is a top view of a LCD with a TOC substrate according toa LCD with a TOC substrate according to an eighth embodiment of thisinvention;

[0038]FIG. 10B is a cross section taken along cut line B-B of FIG. 10A;

[0039]FIG. 10C is a cross section taken along cut line C-C of FIG. 10A;

[0040]FIG. 11A is a top view of a LCD with a TOC substrate according toa LCD with a TOC substrate according to a ninth embodiment of thisinvention;

[0041]FIG. 11B is a cross section taken along cut line B-B of FIG. 11A;

[0042]FIG. 11C is a cross section taken along cut line C-C of FIG. 11A;

[0043]FIG. 12A is a top view of a LCD with a TOC substrate according toa LCD with a TOC substrate according to a tenth embodiment of thisinvention;

[0044]FIG. 12B is a cross section taken along cut line B-B of FIG. 12A;and

[0045]FIG. 12C is a cross section taken along cut line C-C of FIG. 12A.

DETAILED DESCRIPTION OF THE INVENTION

[0046] The present invention provides an active matrix substrate with acolor filter and a black matrix between a switching element such as aTFT and a glass substrate, such structure is referred to as TFT-on-CFsubstrate, hereinafter, referred to as “TOC” substrate.

[0047] A detailed description of the TOC substrate and the method forforming the TOC substrate is given in the following embodiments.

[0048] Method for Forming a TOC Substrate

[0049] Embodiment 1

[0050]FIG. 2A-2G are cross sections showing a method for forming a TOCsubstrate of a liquid-crystal panel according to a first embodiment ofthis invention.

[0051] Referring to FIG. 2A, a first substrate 100 of a transparentinsulating material such as glass is provided. A data line patterned bya first metal layer (M1), also serving as a black matrix (BM) 102 isformed on the substrate 100. The data line/black matrix 102 can be Al,Cr, Mo, Ta, Ti, Cu or their combination for an alloy. A color filter(CF) 104 consisting of the three primary colors, red (R), blue (B) andgreen (G) corresponding to individual pixels is formed on the dataline/black matrix 102 and the substrate 100.

[0052] Referring to FIG. 2B, the black matrix 102 and the color filter104 are covered by an overcoat 106 of a temperature-resistant organicmaterial or silicon-contained low dielectric constant material, on whicha TFT as a switching element is formed as shown in FIG. 2B-2E.

[0053] Referring to FIG. 2C, a second metal layer (M2), such as Al or Alalloy, is formed on the overcoat 106. After defining the metal layerusing lithography and etching, gate lines 108 are formed. The gate lines108 have protruding portions functioning as gate electrodes for thinfilm transistors (TFTs).

[0054] Referring to FIG. 2D, a gate insulating layer 110 is formed onthe gate lines 108 and the overcoat 106. A semiconductor layer 112 andan n-doped layer 114 are sequentially formed on the gate insulatinglayer 110. The gate insulating layer 110 can be silicon nitride, thesemiconductor layer 112 can be amorphous silicon or polysilicon. Then-doped layer 114/the semiconductor layer 112 are etched byphotolithography and etching to define device areas.

[0055] Referring to FIG. 2E, a third metal layer (M3) 116, such as Cr orCr alloy, is formed on the patterned n-doped layer 114 and the gateinsulating layer 110. The metal layer 116/the n-doped layer 114 arepatterned to form source/drain electrodes and source/drain, and a partof the semiconductor layer 112 is therefore exposed.

[0056] Referring to FIG. 2F, a passivation layer 118, such as siliconnitride, is formed on the metal layer 116, the semiconductor layer 112and the gate insulating layer 110.

[0057] Referring to FIG. 2G, an etching is performed to form openings120 and 123 in the passivation layer 118 and opening 122 in thepassivation layer 118, the gate insulating layer 110 and the overcoat106, to expose the surface of the drain electrode 116D, source electrode116S and data line/black matrix 102 respectively. A transparentconducting layer, such as indium tin oxide (ITO), is formed on thepassivation layer 118 in the openings 120 and 122. The transparentconducting layer is then patterned to form a pixel electrode 124connecting the drain electrode 116D through the opening 120 and a localconducting line 126 connecting the source electrode 116S with the dataline/black matrix 102 through the openings 122 and 123. The TOCsubstrate is then obtained.

[0058] Subsequent processes of fabricating upper substrate with commonelectrode thereon and filling liquid crystal therebetween follow.

[0059] Embodiment 2

[0060]FIG. 3A-3G are cross sections showing a method for forming a TOCsubstrate of a liquid-crystal panel according to a second embodiment ofthis invention.

[0061] Referring to FIG. 3A, a first substrate 200 of a transparentinsulating material such as glass is provided. A data line patterned bya first metal layer (M1), also serving as a black matrix (BM) 202 isformed on the substrate 200. The data line/black matrix 202 can be Al,Cr, Mo, Ta, Ti, Cu or their combination for an alloy. A color filter(CF) 204 consisting of the three primary colors, red (R), blue (B) andgreen (G) corresponding to individual pixels is formed on the dataline/black matrix 202 and the substrate 200.

[0062] Referring to FIG. 3B, the black matrix 202 and the color filter204 are covered by an overcoat 206 of an organic material. The overcoat206 can be a photosensitive or non-photosensitive low dielectricconstant material. The overcoat 206 is patterned to form an opening 230to expose the data line/black matrix 102. On the overcoat 206 a TFT as aswitching element is formed as shown in FIG. 3C-3D.

[0063] Referring to FIG. 3C, a gate line 208, such as Al or Al alloy,patterned by a second metal layer (M2) is formed on the overcoat 206.The gate lines 208 have protruding portions functioning as gateelectrodes for thin film transistors (TFTs). A gate insulating layer 210is formed on the gate lines 208 and the overcoat 206. A semiconductorlayer 212 and an n-doped layer 214 are sequentially formed on the gateinsulating layer 210. The gate insulating layer 210 can be siliconnitride, and the semiconductor layer 212 can be amorphous silicon orpolysilicon. The n-doped layer 214/the semiconductor layer 212 areetched by photolithography and etching to define device areas.

[0064] Referring to FIG. 3D, a third metal layer (M3) 216, such as Cr orCr alloy, is formed on the patterned n-doped layer 214 and the gateinsulating layer 210. The metal layer 216/the n-doped layer 214 arepatterned to form source/drain electrodes 216S/216D and source/drain,and a part of the semiconductor layer 212 is therefore exposed to bechannel.

[0065] Referring to FIG. 3E, a passivation layer 218, such as siliconnitride, is formed on the metal layer 216, the semiconductor layer 212and the gate insulating layer 210.

[0066] Referring to FIG. 3F, an etching is performed to form openings220 and 223 in the passivation layer 218 and an opening 222 in thepassivation layer 218 and the gate insulating layer 210, to expose thesurface of the drain electrode 216D, source electrode 216S and dataline/black matrix 202 respectively.

[0067] Referring to FIG. 3G, a transparent conducting layer, such asindium tin oxide (ITO), is formed on the passivation layer 218 in theopenings 220, 223 and 222. The transparent conducting layer is thenpatterned to form a pixel electrode 224 connecting the drain electrode216D through the opening 220 and a local conducting line 226 connectingthe source electrode 216S with the data line/black matrix 202 throughthe opening 223 and 222. The TOC substrate is then obtained.

[0068] Subsequent processes of fabricating upper substrate with commonelectrode thereon and filling liquid crystal therebetween follow.

[0069] Embodiment 3

[0070]FIG. 4A-4G are cross sections showing a method for forming a TOCsubstrate of a liquid-crystal panel according to a third embodiment ofthis invention.

[0071] Referring to FIG. 4A, a first substrate 300 of a transparentinsulating material such as glass is provided. A data line patterned bya first metal layer (M1), also serving as a black matrix (BM) 302 isformed on the substrate 300. The data line/black matrix 302 can be Al,Cr, Mo, Ta, Ti, Cu or their combination for an alloy. A color filter(CF) 304 consisting of the three primary colors, red (R), blue (B) andgreen (G) corresponding to individual pixels is formed on the dataline/black matrix 302 and the substrate 300.

[0072] Referring to FIG. 4B, the black matrix 302 and the color filter304 are covered by an overcoat 306 of an organic material. The overcoat306 can be a photosensitive or non-photosensitive low dielectricconstant material. The overcoat 306 is patterned to form an opening 330to expose the data line/black matrix 302. On the overcoat 306 a TFT as aswitching element is formed as shown in FIG. 4C-4D.

[0073] Referring to FIG. 4C, a gate line 308, such as Al or Al alloy,patterned by a second metal layer (M2) is formed on the overcoat 306.The gate lines 308 have protruding portions functioning as gateelectrodes for thin film transistors (TFTs). A gate insulating layer 310is formed on the gate lines 308 and the overcoat 306. A semiconductorlayer 312 and an n-doped layer 314 are sequentially formed on the gateinsulating layer 310. The gate insulating layer 310 can be siliconnitride, the semiconductor layer 312 can be amorphous silicon orpolysilicon. The n-doped layer 314/the semiconductor layer 312/the gateinsulating layer 310 are etched by photolithography and etching todefine device areas.

[0074] Referring to FIG. 4D, a third metal layer 316, such as Cr or Cralloy, is formed on the patterned n-doped layer 314 and the overcoat306. The metal layer 316/the n-doped layer 314 are patterned to formsource/drain electrodes 316S/316D and source/drain S/D, and a part ofthe semiconductor layer 312 is therefore exposed.

[0075] Referring to FIG. 4E, a passivation layer 318, such as siliconnitride, is formed on the metal layer 316, the semiconductor layer 312and the overcoat 306.

[0076] Referring to FIG. 4F, an etching is performed to form openings320 and 323 in the passivation layer 318 and an opening 322 in thepassivation layer 318, to expose the surface of the drain and sourceelectrodes 316D/316S and data line/black matrix 302 respectively.

[0077] Referring to FIG. 4G, a transparent conducting layer, such asindium tin oxide (ITO), is formed on the passivation layer 318 in theopenings 320, 323 and 322. The transparent conducting layer is thenpatterned to form a pixel electrode 324 connecting the drain electrode316D through the opening 320 and a local conducting line 426 connectingthe source electrode 316S with the data line/black matrix 402 throughthe opening 423 and 422. The TOC substrate is then obtained.

[0078] Subsequent processes of fabricating upper substrate with commonelectrode thereon and filling liquid crystal therebetween follow.

[0079] Embodiment 4

[0080]FIG. 5A-5G are cross sections showing a method for forming a TOCsubstrate of a liquid-crystal panel according to a fourth embodiment ofthis invention.

[0081] Referring to FIG. 5A, a first substrate 400 of a transparentinsulating material such as glass is provided. A data line patterned bya first metal layer (M1), also serving as a black matrix (BM) 402 isformed on the substrate 400. The data line/black matrix 402 can be Al,Cr, Mo, Ta or their combination for an alloy. A color filter (CF) 404consisting of the three primary colors, red (R), blue (B) and green (G)corresponding to individual pixels is formed on the data line/blackmatrix 402 and the substrate 400.

[0082] Referring to FIG. 5B, the black matrix 402 and the color filter404 are covered by an overcoat 406 of an organic material. The overcoat406 can be a photosensitive or non-photosensitive low dielectricconstant material. A gate line 408, such as Al or Al alloy, is formed onthe overcoat 406. The gate lines 408 have protruding portionsfunctioning as gate electrodes for thin film transistors (TFTs). A gateinsulating layer 410 is formed on the gate lines 408 and the overcoat406. A semiconductor layer 412 and an n-doped layer 414 are sequentiallyformed on the gate insulating layer 410. The gate insulating layer 410can be silicon nitride, the semiconductor layer 412 can be amorphoussilicon or polysilicon. The n-doped layer 414 and the semiconductorlayer 412 are etched by photolithography and etching to define deviceareas.

[0083] Referring to FIG. 5C, the overcoat 406 and the gate insulatinglayer 410 are patterned to form an opening 430 to expose the dataline/black matrix 402.

[0084] Referring to FIG. 5D, a transparent conducting layer, such asindium tin oxide (ITO), is formed on the patterned n-doped layer 414 andthe gate insulating layer 410 in the opening 430. The transparentconducting layer/the n-doped layer 414 are patterned to formsource/drain electrodes and source/drain, and a part of thesemiconductor layer 412 is therefore exposed. The transparent conductinglayer is then patterned to form a pixel electrode 424 connecting thedrain D and a local conducting line 426 connecting the source S with thedata line/black matrix 402 through the opening 430.

[0085] Referring to FIG. 5E, a passivation layer 418, such as organicmaterial, is formed on the transparent conducting layer in the activeregion to protect the channel region of the semiconductor layer 412. Thepassivation layer 418 can be a thicker layer with flat surface or aconformal layer. In the figure, the formal is used as an example. TheTOC substrate is then obtained.

[0086] Subsequent processes of fabricating upper substrate with commonelectrode thereon and filling liquid crystal therebetween follow.

[0087] In this embodiment, M3 process is saved, therefore, the pixelelectrode 424 is extends to the drain D to replace the drain electrode,and the local conducting line 426 is formed with the pixel electrode 424and extends to the entire surface of the source S to replace the sourceelectrode.

[0088] Embodiment 5

[0089]FIG. 6A-6H are cross sections showing a method for forming a TOCsubstrate of a liquid-crystal panel according to a fifth embodiment ofthis invention.

[0090] Referring to FIG. 6A, a first substrate 500 of a transparentinsulating material such as glass is provided. A data line patterned bya first metal layer (M1), also serving as a black matrix (BM) 502 isformed on the substrate 500. The data line/black matrix 502 can be Al,Cr, Mo, Ta or their combination for an alloy. A color filter (CF) 504consisting of the three primary colors, red (R), blue (B) and green (G)corresponding to individual pixels is formed on the data line/blackmatrix 502 and the substrate 500.

[0091] Referring to FIG. 6B, the black matrix 502 and the color filter504 are covered by an overcoat 506 of an organic material. The overcoat506 can be a photosensitive or non-photosensitive low dielectricconstant material. On the overcoat 506 a TFT as a switching element isformed as shown in FIG. 6C-6F.

[0092] Referring to FIG. 6C, a gate line 508, such as Al or Al alloy, isformed on the overcoat 506. The gate lines 508 have protruding portionsfunctioning as gate electrodes for thin film transistors (TFTs). A gateinsulating layer 510 is formed on the gate lines 508 and the overcoat506. A semiconductor layer 512 and an n-doped layer 514 are sequentiallyformed on the gate insulating layer 510. The gate insulating layer 510can be silicon nitride, the semiconductor layer 512 can be amorphoussilicon or polysilicon.

[0093] Referring to FIG. 6D, the n-doped layer 514/the semiconductorlayer 512 are etched by photolithography and etching to define deviceareas.

[0094] Referring to FIG. 6E, an opening 530 is formed in the overcoat506 and the gate insulating layer 510.

[0095] Referring to FIG. 6F, a third metal layer (M3) 516, such as Cr orCr alloy, is formed on the patterned n-doped layer 514 and the gateinsulating layer 510 in the opening 530. The metal layer 516/the n-dopedlayer 514 are patterned to form source/drain electrodes 516S/516D andsource/drain S/D, and a part of the semiconductor layer 512 is thereforeexposed. The third metal layer (M3) has two patterns, one is sourceelectrodes 516S connecting to the data line 502 through the opening 530,and the other one is drain electrode 516D.

[0096] Referring to FIG. 6G, a passivation layer 518, such as siliconnitride, is formed on the source electrode 516S, drain electrode 516D,the semiconductor layer 512 and the gate insulating layer 510.

[0097] Referring to FIG. 6H, an etching is performed to form openings520 in the passivation layer 518 to expose the surface of the drainelectrode 516D. A transparent conducting layer, such as indium tin oxide(ITO), is formed on the passivation layer 518 in the opening 520. Thetransparent conducting layer is then patterned to form a pixel electrode524 connecting the drain electrode D through the opening 520. The TOCsubstrate is then obtained.

[0098] Subsequent processes of fabricating upper substrate with commonelectrode thereon and filling liquid crystal therebetween follow.

[0099] In this embodiment, M3 process is performed before forming thepixel electrode 524. The local conducting line connecting the sourceelectrode and the data line/black matrix 502 is the extending sourceelectrode 516S.

[0100] Embodiment 6

[0101]FIG. 7A-7H are cross sections showing a method for forming a TOCsubstrate of a liquid-crystal panel according to a sixth embodiment ofthis invention.

[0102] Referring to FIG. 7A, a first substrate 600 of a transparentinsulating material such as glass is provided. A data line patterned bya first metal layer (M1), also serving as a black matrix (BM) 602 isformed on the substrate 600. The data line/black matrix 602 can be Al,Cr, Mo, Ta or their combination for an alloy. A color filter (CF) 604consisting of the three primary colors, red (R), blue (B) and green (G)corresponding to individual pixels is formed on the data line/blackmatrix 602 and the substrate 600.

[0103] Referring to FIG. 7B, the black matrix 602 and the color filter604 are covered by an overcoat 606 of a low dielectric constantmaterial.

[0104] Referring to FIG. 7C, a gate line 608, such as Al or Al alloy,patterned by a second metal layer (M2) is formed on the overcoat 606.The gate lines 608 have protruding portions functioning as gateelectrodes for thin film transistors (TFTs). A gate insulating layer 610is formed on the gate lines 608 and the overcoat 606. A semiconductorlayer 612 and an n-doped layer 614 are sequentially formed on the gateinsulating layer 610. The gate insulating layer 610 can be siliconnitride, the semiconductor layer 612 can be amorphous silicon orpolysilicon.

[0105] Referring to FIG. 7D, the n-doped layer 614/the semiconductorlayer 612 are etched by photolithography and etching to define deviceareas. An opening 630 is formed in the gate insulating layer 610 and theovercoat 606 to expose the surface of the data line 602.

[0106] Referring to FIG. 7E, a transparent conducting layer, such asindium tin oxide (ITO), is formed on the gate insulating layer 610. Thetransparent conducting layer is then patterned to form a pixel electrode624 in the pixel region.

[0107] Referring to FIG. 7F, a third metal layer (M3) 616, such as Cr orCr alloy, is formed on the patterned n-doped layer 614, the pixelelectrode 624 and the gate insulating layer 610. The metal layer 616/then-doped layer 614 are patterned to form source/drain electrodes616S/616D and source/drain S/D, and a part of the semiconductor layer612 is therefore exposed. The third metal layer (M3) 616 has twopatterns, one is source electrode 616S extends to connect the data line602 through the opening 630, and the other one is drain electrode 616Dconnecting to the pixel electrode 624.

[0108] Referring to FIG. 7G, a passivation layer 618, such as organicmaterial, is formed after forming the pixel electrode 624.

[0109] Referring to FIG. 7H, the passivation 618 is patterned to coverthe source electrode 616S, drain electrode 616D, the semiconductor layer612 but not the pixel electrode 624. The TOC substrate is then obtained.

[0110] Subsequent processes of fabricating upper substrate with commonelectrode thereon and filling liquid crystal therebetween follow.

[0111] In the above-mentioned processes, the passivation 618 is thickerand has a flat surface. Alternatively, a conformal passivation 628, asshown in FIG. 8, can be formed to replace the thicker and flat surfacepassivation 618.

[0112] In this embodiment, M3 process is performed after forming thepixel electrode 624. The local conducting line connecting the sourceelectrode and the data line/black matrix 602 is the extending sourceelectrode 616S.

[0113] In summary, the source electrode of the switching elementdisposed on the color filter and the data line patterned from M1 alsofunctioning as black matrix is connected to the local line. The localline can be formed by M3 process with one opening or pixel electrodeprocess with one or two openings.

[0114] If the local line is patterned from M3, the local line is thesource electrode extends to contact the data line/black matrix. Theopening exposing the surface of the data line/black matrix is formed inthe overcoat and the gate dielectric layer and the gate dielectric layeris not patterned in the active region patterning process (as disclosedin embodiments 5 and 6). Moreover, the pixel electrode can be formedbefore the M3 process (as disclosed in embodiment 6) or after the M3process (as disclosed in embodiment 5).

[0115] If the local line is patterned from transparent conducting layerin the pixel electrode process and one opening for the local line isneeded, the local line and the pixel electrode are patterned at the sametime. The local line is the source electrode extends to contact the dataline/black matrix, and the pixel electrode extends to act as the drainelectrode. Therefore, M3 process is saved. Moreover, the openingexposing the surface of the data line/black matrix is formed in theovercoat and the gate dielectric layer is not patterned in the activeregion patterning process (as disclosed in embodiment 4).

[0116] If the local line is patterned from transparent conducting layerin the pixel electrode process and two openings for the local line areneeded, the local line and the pixel electrode are patterned at the sametime and the two openings are formed to expose the surface of the sourceelectrode and the data line/black matrix respectively. The two openingscan be formed by one or two opening processes. For the former, theopening process is performed after forming the passivation layer, andthe opening is formed in the passivation layer and the overcoat or inthe passivation layer, the gate insulating layer and the overcoat, whichdepends on that if the gate dielectric layer is patterned in the activeregion patterning process or not patterned (as disclosed in embodiment1). For the latter, the first opening process is performed after formingthe overcoat and before forming the gate lines and is formed in theovercoat, and the second opening process is performed after forming thepassivation layer and is formed in the passivation layer or in thepassivation layer and the gate dielectric layer, which depends on thatif the gate dielectric layer is patterned in the active regionpatterning process (as disclosed in embodiments 3) or not patterned (asdisclosed in embodiments 2).

[0117] Structure of a LCD With a TOC Substrate

[0118] Embodiment 7

[0119]FIG. 9A is a top view of a LCD with a TOC substrate according to aseventh embodiment of this invention. FIG. 9B and FIG. 9C are crosssections taken along cut line B-B and C-C of FIG. 9A respectively.

[0120] The switching element, such as TFT, consists of a gate electrode708, a gate insulating layer 710 disposed on the gate electrode 708, asource electrode 716S, a drain electrode 716D and a semiconductor layer(e.g., amorphous silicon) 712 between the source and drain S/D and thegate insulating layer 710. The TFT is covered by a passivation layer718.

[0121] A black matrix (BM) 702 and color filters (CF) 704 consisting ofthe three primary colors, red (R), blue (B) and green (G) correspondingto individual pixels are disposed between the TFT and a lower substrate700. The black matrix 702 also functions as data line which isperpendicular to a gate line 708 having protruding portion P as the gateelectrode 708. The black matrix/data line 702 and the color filter 704are covered by an overcoat 706, on which the TFT is disposed in eachpixel.

[0122] The gate insulating layer 710, in FIG. 9B, is only disposed inthe active region, and the overcoat 706 directly contacts thepassivation layer 718. In fact, the gate insulating layer 710 can extendto between the overcoat 706 and the passviation layer 718.

[0123] A pixel electrode 724 of a transparent conductive material suchas ITO is disposed in each pixel, and connected to the drain electrode716D via an opening 720 formed in the passivation layer 718. A localconducting line 726 of a transparent conductive material such as ITO isdisposed in each pixel, and connects the source electrode 716S with thedata line 702 via an opening 722 formed in the passivation layer 718 andthe overcoat 706.

[0124] As shown in FIG. 9C, the pixel electrode 724 can overlap portionsof the data line 702 due to the thicker stacked insulating layers, thatis, the passivation layer 718, the overcoat 706 and the color filter704. Thus, the capacitance between pixel electrode 724 and underlyingconducting material, data line 702, can be reduced, and an effectivedisplay area, i.e. the area of the pixel electrode 724, can be enlarged.

[0125] In the second opposing substrate 740, a transparent commonelectrode 742 such as ITO, is formed over the entire display area. Onthe facing surfaces of the substrates 740 and 700 are deposited orientedfilms (not shown), rubbed in a given direction.

[0126] Between the substrates 740 and 700, a spacer is appropriatelyplaced for ensuring a given gap, and then these substrates 740 and 700are put together via a sealer with a liquid crystal layer 750therebetween in a manner such that the transparent electrodes 724 and742 face each other.

[0127] In this embodiment, the black matrix/data line 702 is M1, thegate line/gate electrode 708 is M2, and the source electrode 716S andthe drain electrode 716D are M3. The local conducting line 726 and thepixel electrode 724 disposed over the passivation layer 718 are the sametransparent conducting material.

[0128] Embodiment 8

[0129]FIG. 10A is a top view of a LCD with a TOC substrate according toan eighth embodiment of this invention. FIG. 10B and FIG. 10C are crosssections taken along cut line B-B and C-C of FIG. 10A respectively.

[0130] The switching element, such as TFT, consists of a gate electrode808, a gate insulating layer 710 disposed on the gate electrode 808, asource electrode 826, a drain electrode 824 and a semiconductor layer(e.g., amorphous silicon) 812 between the source and the drain S/D andthe gate insulating layer 810. Both the source electrode 826 and thedrain electrode 824 are transparent conducting material. The drainelectrode 824 extends to act as the pixel electrode, and the sourceelectrode 826 is extends to contact the data line 802.

[0131] The TFT is covered by a passivation layer 818, e.g., a siliconnitride layer. The passivation layer 818 covering only the active regioncan be a thicker dielectric layer with flat surface or a conformaldielectric layer. In FIG. 10B, the former is used as an example.

[0132] A black matrix (BM) 802 and color filters (CF) 804 consisting ofthe three primary colors, red (R), blue (B) and green (G) correspondingto individual pixels are disposed between the TFT and a lower substrate800. The black matrix 802 also functions as data line which isperpendicular to a gate line 808 having protruding portion P as the gateelectrode 808. The black matrix/data line 802 and the color filter 804are covered by an overcoat 806, on which the TFT is disposed in eachpixel.

[0133] The gate insulating layer 810, in FIG. 10B, is only disposed inthe active region, and the overcoat 806 directly contacts thepassivation layer 818. In fact, the gate insulating layer 810 can extendto between the overcoat 806 and the passviation layer 818.

[0134] As shown in FIG. 10C, the pixel electrode 824 can overlapportions of the data line 802 due to the thicker stacked insulatinglayers, that is, the overcoat 806 and the color filter 804. Thus, thecapacitance between pixel electrode 824 and underlying conductingmaterial, data line 802, can be reduced, and an effective display area,i.e. the area of the pixel electrode which is a portion of the layer824, can be enlarged.

[0135] In the second opposing substrate 840, a transparent commonelectrode 842 such as ITO, is formed over the entire display area. Onthe facing surfaces of the substrates 840 and 800 are deposited orientedfilms (not shown), rubbed in a given direction.

[0136] Between the substrates 840 and 800, a spacer is appropriatelyplaced for ensuring a given gap, and then these substrates 840 and 800are put together via a sealer with a liquid crystal layer 850therebetween in a manner such that the transparent electrodes face eachother.

[0137] In this embodiment, the black matrix/data line 802 is M1, thegate line/gate electrode 808 is M2, and the source electrode/localconducting line 826 and the drain electrode/pixel electrode 824 aretransparent conducting layer.

[0138] Embodiment 9

[0139]FIG. 11A is a top view of a LCD with a TOC substrate according toa ninth embodiment of this invention. FIG. 11B and FIG. 11C are crosssections taken along cut line B-B and C-C of FIG. 11A respectively.

[0140] The switching element, such as TFT, consists of a gate electrode908, a gate insulating layer 910 disposed on the gate electrode 908, asource electrode 916S, a drain electrode 916D and a semiconductor layer(e.g., amorphous silicon) 912 between the source and drain S/D and thegate insulating layer 910. The TFT is covered by a passivation layer918. The source electrode 916S and the drain electrode 916D are metalmaterial, and the source electrode 916S is extends to contact the dataline 902 through opening 930 in the gate insulating layer 910 and theovercoat 906.

[0141] A black matrix (BM) 902 and color filters (CF) 904 consisting ofthe three primary colors, red (R), blue (B) and green (G) correspondingto individual pixels are disposed between the TFT and a lower substrate900. The black matrix 902 also functions as data line which isperpendicular to a gate line 908 having protruding portion P as the gateelectrode 908. The black matrix/data line 902 and the color filter 904are covered by an overcoat 906, on which the TFT is disposed in eachpixel.

[0142] The gate insulating layer 910, in FIG. 11B, is substantiallydisposed on the entire substrate 900. In fact, the gate insulating layer710 can be only disposed in the active region.

[0143] A pixel electrode 924 of a transparent conductive material suchas ITO is disposed in each pixel on the passivation layer 918. The pixelelectrode 924 is connected to the drain electrode 916D via an opening920 formed in the passivation layer 918.

[0144] As shown in FIG. 11C, the pixel electrode 924 can overlapportions of the data line 902 due to the thicker stacked insulatinglayers, that is, the passivation layer 918, the gate insulating layer910, the overcoat 906 and the color filter 904. Thus, the capacitancebetween pixel electrode 924 and underlying conducting material, dataline 902, can be reduced, and an effective display area, i.e. the areaof the pixel electrode 924, can be enlarged.

[0145] In the second opposing substrate 940, a transparent commonelectrode 942 such as ITO, is formed over the entire display area. Onthe facing surfaces of the substrates 940 and 900 are deposited orientedfilms (not shown), rubbed in a given direction.

[0146] Between the substrates 940 and 900, a spacer is appropriatelyplaced for ensuring a given gap, and these substrates 940 and 900 areput together via a sealer with a liquid crystal layer 950 therebetweenin a manner such that the transparent electrodes face each other.

[0147] In this embodiment, the black matrix/data line 902 is M1, thegate line/gate electrode 908 is M2, and the source electrode/localconducting line 916S and the drain electrode 916D are M3. The pixelelectrode 924 is disposed over the passivatoin layer 918.

[0148] Embodiment 10

[0149]FIG. 12A is a top view of a LCD with a TOC substrate according toa tenth embodiment of this invention. FIG. 12B and FIG. 12C are crosssections taken along cut line B-B and C-C of FIG. 12A respectively.

[0150] The switching element, such as TFT, consists of a gate electrode1008, a gate insulating layer 1010 disposed on the gate electrode 1008,a source electrode 1016S, a drain electrode 1016D and a semiconductorlayer (e.g., amorphous silicon) 1012 between the source and drain S/Dand the gate insulating layer 1010. The TFT is covered by a passivationlayer 1018. The source electrode 1016S and the drain electrode 1016D aremetal. The source electrode 1016S is extends to contact the data line1002 and the drain electrode 1016D is extends to contact and cover aportion of the pixel electrode 1024.

[0151] A black matrix (BM) 1002 and color filters (CF) 1004 consistingof the three primary colors, red (R), blue (B) and green (G)corresponding to individual pixels are disposed between the TFT and alower substrate 1000. The black matrix 1002 also functions as data linewhich is perpendicular to a gate line 1008 having protruding portion Pas the gate electrode 1008. The black matrix/data line 1002 and thecolor filter 1004 are covered by an overcoat 1006, on which the TFT isdisposed in each pixel.

[0152] The gate insulating layer 1010, in FIG. 12B, is substantiallydisposed on the entire substrate 1000. In fact, the gate insulatinglayer 1010 can be only disposed in the active region.

[0153] A pixel electrode 1024 of a transparent conductive material suchas ITO is disposed in each pixel on the overcoat 1006 below the drainelectrode 1016D.

[0154] As shown in FIG. 12C, the pixel electrode 1024 can overlapportions of the data line 1002 due to the thicker stacked insulatinglayers, that is, the gate insulating layer 1010, the overcoat 1006 andthe color filter 1004. Thus, the capacitance between pixel electrode1024 and underlying conducting material, data line 1002, can be reduced,and an effective display area, i.e. the area of the pixel electrode1024, can be enlarged.

[0155] In the second opposing substrate 1040, a transparent commonelectrode 1042 such as ITO, is formed over the entire display area. Onthe facing surfaces of the substrates 1040 and 1000 are depositedoriented films (not shown), rubbed in a given direction.

[0156] Between the substrates 1040 and 1000, a spacer is appropriatelyplaced for ensuring a given gap, and then these substrates 1040 and 1000are put together via a sealer with a liquid crystal layer 1050therebetween in a manner such that the transparent electrodes face eachother.

[0157] In this embodiment, the black matrix/data line 1002 is M1, thegate line/gate electrode 1008 is M2, and the source electrode/localconducting line 1016S and the drain electrode 1016D are M3. The pixelelectrode 1024 is disposed below the drain electrode 1016D.

[0158] In summary, the source electrode of the switching elementdisposed on the color filter and the data line from M1 also functioningas black matrix is connected to the local line. The local line can be anindependent conducting line disposed over the passivation layer andconnecting to the source electrode and the data line through twoopenings. Alternatively, the local line can be extending from the sourceelectrode.

[0159] If the local line is the above-mentioned independent conductingline, the local line and the pixel electrode are the same transparentconducting material. The gate insulating layer can be disposed betweenthe passivation layer and the overcoat (as disclosed in embodiment 7).

[0160] As for the local line extending from the source electrode, thesource electrode can be a metal material or transparent conductingmaterial.

[0161] If the source electrode is a metal material, that is, M3, thedrain electrode can be disposed over the pixel electrode (as disclosedin embodiment 9) or under the pixel electrode (as disclosed inembodiment 10). In such a situation, the gate insulating layer should bedisposed substantially over the entire lower substrate.

[0162] If the source electrode is a transparent conducting material, thedrain electrode extends to act as the pixel electrode (as disclosed inembodiment 8). In such situation, the gate insulating layer should bedisposed substantially over the entire lower substrate.

[0163] While the invention has been described by way of example and interms of the preferred embodiments, it is to be understood that theinvention is not limited to the disclosed embodiments. To the contrary,it is intended to cover various modifications and similar arrangements(as would be apparent to those skilled in the art). Therefore, the scopeof the appended claims should be accorded the broadest interpretation toencompass all such modifications and similar arrangements.

What is claimed is:
 1. A liquid crystal display, comprising: a firstsubstrate; a second substrate having a common electrode opposite thefirst substrate; a switching device disposed on a portion of the firstsubstrate, and the switching device coupled between a data line and apixel electrode; a color filter layer disposed between the switchingdevice and the first substrate; and the data line disposed between thecolor filter and the first substrate.
 2. The liquid crystal display asclaimed in claim 1, wherein the data line is a black matrix.
 3. Theliquid crystal display as claimed in claim 1, wherein the switchingdevice is a back channel etched thin film transistor.
 4. The liquidcrystal display device as claimed in claim 1, further comprising anovercoat between the color filter and the switching device.
 5. Theliquid crystal display device as claimed in claim 1, further comprisinga passivation layer covering the switching device.
 6. The liquid crystaldisplay device as claimed in claim 1, wherein a local conducting lineconnects the switching device and the data line, and the localconducting line and the pixel electrode are transparent conductingmaterial.
 7. The liquid crystal display device as claimed in claim 6,wherein the pixel electrode is disposed on the overcoat and contacts theovercoat.
 8. The liquid crystal display device as claimed in claim 6,wherein a drain electrode of the switching device extends to act as thepixel electrode, and a source electrode of the switching device isextends to contact the data line.
 9. The liquid crystal display deviceas claimed in claim 6, wherein the pixel electrode is disposed on apassivation layer covering the switching device.
 10. The liquid crystaldisplay device as claimed in claim 9, wherein the switching devicecomprises a gate insulating layer between the passivation layer and theovercoat.
 11. The liquid crystal display device as claimed in claim 1,wherein the switching device comprises a drain electrode connecting tothe pixel electrode and a source electrode extending to the data line.12. The liquid crystal display device as claimed in claim 11, whereinthe pixel electrode is under the drain electrode.
 13. The liquid crystaldisplay device as claimed in claim 11, wherein the switching devicecomprises a gate insulating layer on the overcoat, the pixel electrodeis disposed on the gate insulating layer and contacts the gateinsulating layer.
 14. The liquid crystal display device as claimed inclaim 11, wherein the pixel electrode is over the drain electrode. 15.The liquid crystal display device as claimed in claim 11, wherein thepixel electrode is disposed on a passivation layer covering theswitching device.
 16. A method for manufacturing a liquid crystaldisplay comprising the steps of: providing a substrate; forming a dataline on the substrate; forming a color filter on the data line and thesubstrate; forming an overcoat on the color filter; and forming aswitching device on the overcoat, and the switching device coupledbetween a data line and a pixel electrode.
 17. The method formanufacturing the liquid crystal display as claimed in claim 16, whereinthe data line is a black matrix.
 18. The method for manufacturing theliquid crystal display as claimed in claim 16, wherein the switchingdevice is a back-channel-etched thin film transistor.
 19. The method formanufacturing the liquid crystal display device as claimed in claim 16,further comprising forming an overcoat between the color filter and theswitching device.
 20. The method for manufacturing the liquid crystaldisplay device as claimed in claim 16, further comprising forming apassivation layer covering the switching device.
 21. The method formanufacturing the liquid crystal display device as claimed in claim 16,wherein a local conducting line connects the switching device and thedata line, and the local conducting line and the pixel electrode aretransparent conducting material.
 22. The method for manufacturing theliquid crystal display device as claimed in claim 21, wherein the pixelelectrode is disposed on the overcoat and contacts the overcoat.
 23. Themethod for manufacturing the liquid crystal display device as claimed inclaim 21, wherein a drain electrode of the switching device extends toact as the pixel electrode, and a source electrode of the switchingdevice is extends to contact the data line.
 24. The method formanufacturing the liquid crystal display device as claimed in claim 21,wherein the step of forming the switching device on the overcoatcomprises: forming a gate line on the overcoat; forming a gateinsulating layer, a semiconductor layer and an n-doped layer on the gateline and the overcoat; patterning the n-doped layer and thesemiconductor layer; forming a first opening in the gate insulatinglayer and the overcoat exposing a surface of the data line; forming atransparent conducting layer on the n-doped layer and the gateinsulating layer and in the first opening; patterning the transparentconducting layer and the n-doped layer to form the pixel electrode andthe local conducting line, wherein the pixel electrode extends to act asa drain electrode and the local conducting line extends to act as asource electrode; and forming a passivation layer covering the switchingdevice.
 25. The method for manufacturing the liquid crystal displaydevice as claimed in claim 21, wherein the pixel electrode is disposedon a passivation layer covering the switching device.
 26. The method formanufacturing the liquid crystal display device as claimed in claim 25,wherein the step of forming the switching device on the overcoatcomprises: forming a gate line on the overcoat; forming a gateinsulating layer on the gate line and the overcoat; forming andpatterning a semiconductor layer and an n-doped layer on the gate lineand the gate insulating layer; forming a metal layer on thesemiconductor layer and the gate insulating layer; patterning the metallayer and the n-doped layer to form a source electrode and a drainelectrode; forming a passivation layer covering the source electrode,the drain electrode and the gate insulating layer; forming a firstopening and a second opening in the passivation layer and a thirdopening in the passivation layer, the gate insulating layer and theovercoat; forming a transparent conducting layer on the passivationlayer and in the first, second and third openings; and patterning thetransparent conducting layer to form the pixel electrode connecting tothe drain electrode through the first opening and the local conductingline connecting the source electrode and the data lines through thesecond and third openings respectively.
 27. The method for manufacturingthe liquid crystal display device as claimed in claim 25, wherein thestep of forming the switching device on the overcoat comprises: forminga first opening in the overcoat to expose a surface of the data line;forming a gate line on the overcoat; forming a gate insulating layer onthe gate line, the data line and the overcoat; forming and patterning asemiconductor layer and an n-doped layer on the gate line and the gateinsulating layer; forming a metal layer on the semiconductor layer andthe gate insulating layer; patterning the metal layer and the n-dopedlayer to form a source electrode and a drain electrode; forming apassivation layer covering the source electrode, the drain electrode andthe gate insulating layer; forming a second opening and a third openingin the passivation layer and first opening extending into thepassivation layer and the gate insulating layer; forming a transparentconducting layer on the passivation layer and in the first, second andthird openings; and patterning the transparent conducting layer to formthe pixel electrode connecting to the drain electrode through the secondopening and the local conducting line connecting to the source electrodeand the data line through the first and third openings respectively. 28.The method for manufacturing the liquid crystal display device asclaimed in claim 25, wherein the step of forming the switching device onthe overcoat comprises: forming a first opening in the overcoat toexpose a surface of the data line; forming a gate line on the overcoat;forming and patterning a gate insulating layer, a semiconductor layerand an n-doped layer on the gate line and the overcoat; forming a metallayer on the semiconductor layer and the overcoat; patterning the metallayer and the n-doped layer to form a source electrode and a drainelectrode; forming a passivation layer covering the source electrode,the drain electrode and the overcoat; forming a second opening and athird opening in the passivation layer and the first opening extendinginto the passivation layer; forming a transparent conducting layer onthe passivation layer and in the first, second and third openings; andpatterning the transparent conducting layer to form the pixel electrodeconnecting to the drain electrode through the second opening and thelocal conducting line connecting the source electrode and the data linethrough the first and third openings respectively.
 29. The method formanufacturing the liquid crystal display device as claimed in claim 16,wherein the switching device comprises a source electrode connecting tothe pixel electrode and a drain electrode extending to contact the dataline.
 30. The method for manufacturing the liquid crystal display deviceas claimed in claim 29, wherein the step of forming the switching deviceon the overcoat comprises: forming a gate line on the overcoat; forminga gate insulating layer on the overcoat; forming and patterning asemiconductor layer and an n-doped layer on the gate line and the gateinsulating layer; forming a first opening in the gate insulating layerand the overcoat to expose a surface of the data line; forming a metallayer on the semiconductor layer and the gate insulating layer and inthe first opening; patterning the metal layer and the n-doped layer toform a source electrode extending to contact the date line and a drainelectrode; forming a passivation layer covering the source electrode,the drain electrode and the overcoat; forming a second opening in thepassivation layer to expose a surface of the drain electrode; forming atransparent conducting layer on the passivation layer and in the secondopening; and patterning the transparent conducting layer to form thepixel electrode connecting to the drain electrode through the secondopening.
 31. The method for manufactureing the liquid crystal displaydevice as claimed in claim 25, wherein the step of forming the switchingdevice on the overcoat comprises: forming a gate line on the overcoat;forming a gate insulating layer on the overcoat; forming and patterninga semiconductor layer and an n-doped layer on the gate line and the gateinsulating layer; forming a first opening in the gate insulating layerand the overcoat to expose a surface of the data line; forming the pixelelectrode on the gate insulating layer; forming a metal layer on thesemiconductor layer, the pixel electrode and the gate insulating layerand in the first opening; patterning the metal layer and the n-dopedlayer to form a source electrode extending to contact the date line anda drain electrode extending to cover the pixel electrode; forming apassivation layer covering the switching device.
 32. The method formanufacturing the liquid crystal display device as claimed in claim 29,wherein the pixel electrode is under the drain electrode.
 33. The methodfor manufacturing the liquid crystal display device as claimed in claim29, wherein the switching device comprises a gate insulating layer onthe overcoat, the pixel electrode is disposed on the gate insulatinglayer and contacts the gate insulating layer.
 34. The method formanufacturing the liquid crystal display device as claimed in claim 29,wherein the pixel electrode is over the drain electrode.
 35. The methodfor manufacturing the liquid crystal display device as claimed in claim29, wherein the pixel electrode is disposed on a passivation layercovering the switching device.